Insect screen with improved optical properties

ABSTRACT

An insect screen made from fibers in a warp and fill construction defining openings having a warp dimension and a fill dimension, both of said warp and fill dimensions being equal to or less than about 0.04 inches and equal to or larger than about 0.01 inches, said fibers having a diameter of equal to or greater than about 0.002 inches and less than about 0.007 inches. The present invention is an improved insect screen designed to serve the primary purpose of keeping out very small insects and pests while maximizing visual clarity, light transmission, and airflow.

RELATED APPLICATIONS

[0001] This application is a continuation-in-part of U.S. patentapplication Ser. No. 10/405,104, filed Mar. 31, 2003.

FIELD OF THE INVENTION

[0002] The present invention relates to screens, and more particularly,to woven insect screens.

BACKGROUND OF THE INVENTION

[0003] Insect screens have been in use on windows and doors for morethan a century. Their intended purpose is to keep out common insectssuch as flies, moths, mosquitoes, and bees as well as other creaturessuch as birds and rodents. Insect screens are used for many applicationssuch as windows, doors, patio enclosures, pool enclosures, garage doors,and more.

[0004] Insect screens are typically woven from various types of fibers,historically starting from materials such as horsehair and linen. Forgreater durability, screens evolved to woven wire made of low-carbonsteel, however, the steel was known to rust. Bronze, stainless steel,and aluminum wire replaced steel. In the 1970's, screens woven fromvinyl (PVC) coated fiberglass fibers were introduced. These screensoffered benefits of durability, light weight, ease of weaving, and easeof installation. Vinyl coated fiberglass screens offered a significantimprovement over metal screens for ease of installation since commontools can cut and trim the screen materials without leaving sharp wiresthat can create safety issues. Vinyl coated fiberglass screens havebecome the industry standard for common insect screens.

[0005] Insect screens are primarily designed to exclude insects from anenclosed area while still offering the sensation of the outdoors bytransmitting light, sound, and airflow. However, the basic woven fiberconstruction of a screen will inherently compromise visibility andairflow due to blockage of open area by the fibers.

[0006] Visual quality can be expressed in terms of both lighttransmission as well as clarity. Light transmission relates to thequantity of light that passes through the screen. Clarity is a measureof image distortion cause by the interference of the fibers with thevisual image as viewed through the screen. Woven screens can alsorestrict airflow causing reduced ventilation and reduced sensation of“feeling the breeze.”

[0007] Insect screen constructions have been optimized over the years inorder to reach a compromise between excluding most insects and enablingreasonable visibility and airflow. Typically, the most common insectscreens used today include 16×16, 18×14, 18×16, and 18×18 meshes ofplain weave construction. “Mesh” describes the number of openings andfractional parts of an opening per linear inch. With a plain weave, meshcount typically corresponds with the fiber count for number of fibersper inch in the warp and fill. With increased mesh or fiber count, theopening or hole size decreases with fiber diameter remaining constant.In certain geographical regions where small biting midges and sandflies, also known as no-see ‘ums, are present, 20×20 mesh screening isrecommended to offer exclusion of these insects. However, the tradeofffor excluding small insects, such as midges, is not only a reduction invisual quality but also a reduction in airflow due to the loss of openarea from the increased number of fibers. For example, to compensate forthe loss of airflow caused by a 20×20 mesh screen, it is recommended todouble the amount of screen surface area used for ventilation in orderto equal the amount of unscreened window normally used; i.e., twoscreened open windows are required to equal the airflow of oneunscreened open window.

[0008] Although the term mesh is typically used to describe the relativehole size of woven screening, this term gives no recognition to thediameter of the fiber or wire, and thus the mesh number does not alwayshave a relationship to the size of the hole in the screen. Hole size,aperture, or opening is defined as the dimension between adjacentparallel wires, usually expressed in decimal parts of an inch. It can becalculated using the equation below for each of the warp and filldirections of the screen. Fill is defined as fibers or wires runningacross the width or short way of the woven cloth during weaving, alsoreferred to as shute and weft. Warp is defined as the fibers of wirerunning lengthwise during weaving.

[0009] Opening=(1/N)-D

[0010] N=Wires per inch

[0011] D=Wire diameter (inches)

[0012] This equation remains accurate for screens woven from wire andfibers where the diameter of the material is unchanging. In the case ofPVC coated fiberglass, the coating can melt flow during processingthereby changing the original fiber dimensions. The above formula can beused for these materials as well providing that the fiber diameter ismeasured in the final state assuming uniform fiber size and parallelfibers.

[0013] When comparing screens of different materials and constructions,it is important to make these comparisons using similar opening or holesize dimensions since the opening dimension provides the criticaldimension for insect exclusion. Typically, insect screens can be definedby the fiber material, fiber diameter, and weaving construction (mesh orfibers per inch).

[0014] In order to understand the opening size commonly used in insectscreening, a sampling of various commercial insect screens was compared.The properties and calculated openings are shown in the table below.Calculations in the table assumed mesh and fiber count to be identical.In addition to commercial screens, also included are examples of insectwire screens specified as American National Standards approved by theInsect Screening Weavers Association in 1990 document ANSI/IWS 089-1990.Supplier Material Mesh Wire Dia (In) Warp Opening (in) Fill Opening (in)Connecticut Screen PVC-Fiberglass 20 × 20 0.013 0.0370 0.0370 WorksConnecticut Screen PVC-Fiberglass 18 × 14 0.013 0.0426 0.0584 WorksWright Screens, PVC-Fiberglass 18 × 16 0.011 0.0446 0.0515 LLC AmericanNational Aluminum 18 × 16 0.011 0.0446 0.0515 Standard American NationalBronze 18 × 14 0.011 0.0466 0.0604 Standard American National CarbonSteel 18 × 14 0.009 0.0466 0.0624 Standard Marco Specialty GalvanizedSteel 18 × 14 0.009 0.0466 0.0624 Steel Marco Specialty Bronze 18 × 140.011 0.0466 0.0604 Steel TWP Inc. Stainless Steel 18 × 14 0.009 0.04660.0624 TWP Inc. Copper 16 × 16 0.011 0.0515 0.0515

[0015] As evidenced by the examples in the table, fiber or wire commonlyused for window insect screening is known to have diameters ranging from0.009 to 0.013 inches. It is important to note that the calculated holewidth for the fiberglass screens used the indicated wire diameter asopposed to the actual wire diameter in the finished screen. Hole sizeand open area of PVC coated fiberglass screens typically have valuesless than the expected values due to flow of the PVC coating.

[0016] Various polymeric materials have been used for specializedgreenhouse screening. This type of screening is used for the purposes ofrestricting very small insects and thereby negating the need to usepesticides. These screens are typically woven from small diameterpolyethylene and nylon fibers into tight screen constructions to havevery small hole sizes of less than 0.02 inches. These screens can bepurchased from Green-tek under the names No-Thips and Virus Vectorscreens. These types of insect screens are not intended for residentialinsect screen applications because of poor visual claritycharacteristics and limited airflow. Furthermore, fiber materials suchas polyethylene and nylon are known to have poor UV radiation (sunlight)resistance, which can degrade the fiber strength over time. Thus,polyethylene and nylon screens are typically limited to a lifetime ofthree years or less. The lifetime of residential screens is expected tobe many years, often five, ten, or more. For these reasons, polyethyleneand nylon are not used as insect screens for windows, doors, patios, andother residential applications.

[0017] Typically, insect screens have either the warp or fill holedimension to be less than about 0.05 inches in order to exclude mostcommon flying insects, with the other hole dimension being larger thanabout 0.03 inches in order to offer acceptable airflow, visual clarity,and/or light transmission. In other words, the warp and fill dimensionare not both below about 0.03 inches, nor are they both above about 0.05inches. This hole size range for residential window screening isconsistent with products offered and sold as window/insect screen. Oneexample of screen sold for insect exclusion with a hole size larger than0.05 inches in both the warp and fill dimensions is made of copper wirewith a 16×16 mesh as described in the table above. This screen uniquelyoffers a historically accurate aesthetic appeal and does not fall intothe hole size ranges depicted by the American National Standards of theInsect Screening Weavers Associations.

[0018] It has been recognized that optical attenuation and lightdistortion of window screens can be undesirable. U.S. Pat. No. 5,139,076describes a distortion free window screen made from transparent fiberoptic cables. It is the intention of this patent to increase the lighttransmission of the screen while minimizing distortion of the lightpassing through the fibers. They attempt to accomplish this by usingclear, round cross-section, fibers. Although the total lighttransmission can be improved with clear fibers, distortion and glarewill still exist due to reflection and refraction of the light raysthrough the clear fiber.

[0019] Another attempt to minimize the drawbacks of screen see-throughvisibility is described in U.S. Pat. No. 5,392,835. This patentdescribes a roll-type retractable insect screen that can be retractedwhen not in use. This type of technology enables the user to remove thescreen from the field of view when not in use so as to provide a clearunobstructed view.

[0020] There are long-felt needs associated with current insect screentechnology. These include the needs for improvement to opticaltransmission characteristics and airflow characteristics. In particular,there has been a long-felt need in the industry for an “invisiblescreen,” one that is less visible and hence less obstructive of the viewthrough the screen. It is surprising that using smaller fibers for thescreen construction would be effective because more fibers would beneeded to provide the same hole sizes, thus not providing any realimprovement in visibility.

SUMMARY OF THE INVENTION

[0021] The present invention provides an insect screen made from fibersin a warp and fill construction defining openings having a warpdimension and a fill dimension, both of said warp and fill dimensionsbeing equal to or less than about 0.04 inches and equal to or largerthan about 0.01 inches, said fibers having a diameter of equal to orgreater than about 0.002 inches and less than about 0.007 inches. Thepresent invention is an improved insect screen designed to serve theprimary purpose of keeping out very small insects and pests whilemaximizing visual clarity, light transmission, and airflow. In thisaspect, The present invention provides an insect screen where the visualclarity factor is equal to or greater than about 50%, preferably greaterthan about 60%, still more preferably greater than or equal to about70%, even more preferably greater than or equal to about 80%, and mostpreferably about 85%. Also in this aspect, the present inventionprovides an insect screen with a total light transmission equal to about50% or greater, preferably about 60% or greater, more preferably about70% or greater, still more preferably about 80% or greater, and mostpreferably about 85% or greater. Also in this aspect, the presentinvention provides an insect screen with a specular light transmissionof about 50% or greater, preferably about 60% or greater, morepreferably about 70% or greater, and most preferably about 80% orgreater.

[0022] In another aspect, the present invention is an improved insectscreen designed to serve the primary purpose of keeping out insects andpests while maximizing visual clarity, light transmission, and airflow.The present invention employs the use of small diameter fibers woveninto an insect screen with standard hole size construction. Thisconstruction is a warp and fill construction defining openings having awarp dimension and a fill dimension, at least one of the warp and filldimensions being less than about 0.05 inches and the other of the warpand fill dimensions being larger than about 0.03 inches.

[0023] In this aspect, the present invention provides an insect screenwoven from fibers with small diameters of about 0.007 inches or less,preferably diameters of about 0.006 inches or less, and more preferablyof diameters of about 0.005 inches or less, still more preferably wherethe diameters are about 0.004 inches or less, and most preferably ofabout 0.003 inches or less.

[0024] Also in this aspect, the present invention provides an insectscreen with a total light transmission equal to about 75% or greater,preferably about 80% or greater, and more preferably about 85% orgreater. Also in this aspect, this invention provides a non-metallicinsect screen with a total light transmission greater than or equal toabout 60%, preferably about 65% or greater, more preferably about 70% orgreater, even more preferably about 75% or greater, then even morepreferably of about 80% or greater and most preferably of about 85% orgreater.

[0025] Also in this aspect, the present invention provides an insectscreen with a specular light transmission of about 75% or greater,preferably about 80% or greater. Also in this aspect, this presentinvention provides a non-metallic insect screen with a specular lighttransmission greater than or equal to about 60%, preferably about 65% orgreater, and even more preferably about 70% or greater, then even morepreferable of about 75% or greater, and most preferable of about 80% orgreater.

[0026] Also in this aspect, the present invention provides an insectscreen where the visual clarity factor is equal to or greater than about55%, preferably greater than about 60%, still more preferably greaterthan or equal to about 65%, even more preferable greater than or equalto about 70%, and most preferable greater than or equal to about 75%.Also in this aspect, the present invention provides a non--metallicinsect screen where the visual clarity factor is equal to or greaterthan about 55% preferably about 60% or greater, and even more preferablyabout 65% or greater, then even more preferably about 70% or greater,and most preferably about 75% or greater.

[0027] The present invention provides an insect screen with the aboveelements wherein the fibers are clear, or in the preferred embodiment,where the fibers are dark or opaque to minimize the glare factors causedby refraction and reflectance.

[0028] The present invention provides a non-metallic insect screen wovenfrom fluoropolymer fibers, the fibers being from the fluoropolymer classincluding ETFE, ECTFE, PTFE, FEP, MFA, PFA, PEEK, and PVDF or hybridsthereof. PVDF fibers are particularly preferred. The invention alsoprovides for metal fibers.

[0029] The present invention provides an insect screen made fromnon-metallic fibers wherein a substantial number of fibers are bonded atthe fiber intersections to form bonded intersections, and the fibers arebonded so as to maintain the original fiber cross section (preferablysubstantially round) in non-bonded regions between said bondedintersections. Preferably, such bonded intersections are thermallybonded, and more preferably thermally bonded via ultrasonic energy.

[0030] The present invention provides insect screen fabric which can beeasily mounted and framed using conventional techniques such as splineand groove attachment.

[0031] In another aspect, this invention provides a method of making awoven fiber screen by providing non-metallic fibers having across-section; weaving the non-metallic fibers into a warp and fillconstruction defining openings having a warp dimension and a filldimension, the fibers in the warp dimension and the fibers in the filldimension intersecting at intersections; and ultrasonically bonding thefibers at at least some of the intersections to form bondedintersections without substantially disturbing the cross-section of thefibers between the bonded intersections.

BRIEF DESCRIPTION OF THE DRAWING

[0032]FIG. 1 is an oblique cross-sectional view of an embodiment of thepresent invention.

[0033]FIG. 2 is a schematic of a device used to measure the opticalproperties of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0034] The present invention is an improved insect screen material withremarkable light transmission and airflow properties. An embodiment ofthe present invention is illustrated in FIG. 1. An insect screen 10 isshown, formed of fibers 21. Fibers 21 are woven into a warp and fillconstruction. In this embodiment, the warp dimension is designated byarrow A, the fill dimension by arrow B, although these directions couldof course be reversed, depending on the direction of weaving. Fibers 21intersect at intersections 22, and define openings 25. Screen 10 ispreferably mounted in a frame 12 attached to a structure 14. Frame 12preferably has a spline 16 and a groove 18 construction for securelyattaching screen 10 thereto.

[0035] In a preferred embodiment, this invention involves the use offibers with diameters of about 0.007 inches or less woven into an insectscreen having a particular hole size and construction. In otherpreferred embodiments, the fibers have diameters of less than about0.006 inches, less than about 0.005 inches, less than about 0.004inches, less than about 0.003 inches, to about 0.002 inches. By usingfibers that are significantly smaller than current insect screen fibers,the light transmission and airflow increases substantially. Furthermore,by decreasing the fiber diameter, the fibers tend to become lessvisually apparent, thus creating an insect screen that is much morevisually appealing.

[0036] The screens of the present invention can be of a variety of fibermaterials. These materials can include, but are not limited to, standardmetal materials such as aluminum, steel, bronze, copper, and stainlesssteel. These materials can also include non-metallic materials such aspolyester, nylon, PVC coated fiberglass and others.

[0037] A factor that can affect screen durability is ultraviolet (UV)degradation, typically caused by sunlight exposure. It is known thatmost non-metallic fibers will degrade and lose strength after a fewyears of sunlight exposure due to UV degradation. PVC coated fiberglassscreens exhibit this degradation with the PVC coating turning white andflaking off. It can be desirable to use non-metallic fibers as a screenmaterial, but it becomes challenging to meet durability expectations ifsmall fibers are used. Small diameter fibers already can be weaker inbreakstrength than larger diameter fibers and with further UVdegradation the fiber can fail prematurely. With these limitations, itis challenging for small diameter non-metallic insect screens to meetthe typical industry expectations for lifetimes of five to ten years ormore.

[0038] A novel aspect of the present invention is that in a preferredembodiment it incorporates the use of fluoropolymer fibers as theprimary fiber for woven insect screen. Fluoropolymers offer a uniqueadvantage for this application since they typically have extremely lowUV light absorption, which enables the material to remain virtuallyunaffected when exposed to these often harmful wavelengths.Fluoropolymers that may be suitable for this application include, butare not limited to, fluoropolymers in the classes of ethylenetetrafluoroethylene (ETFE), ethylene chlorotrifluoroethylene (ECTFE),polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP),perfluoroalkoxy (PFA), tetrafluoroethylene perfluoromethylvinylether(MFA), tetrafluoroethylene hexafluoropropylene vinylidene fluoride(THV), polyetheretherketone (PEEK), and polyvinylidene fluoride (PVDF).Attributes that should be considered in material selection includestrength, elongation, modulus, and processibility.

[0039] One of the preferred fluoropolymer fiber materials of thisinvention is PVDF. This material is readily melt processible therebyenabling fibers of uniform small diameters to be cost effectivelyfabricated. This material is also one of the stronger fluoropolymermaterials thus offering enhanced durability. Also, this material can bebonded to itself through various bonding techniques thus being able toproduce a preferable insect screen fabric where a substantial number ofthe fibers are bonded at their intersection points for improvedstability.

[0040] Insect screens are typically manufactured by weaving monofilamentor multifilament fibers using standard weaving processes. Weavingconstructions can include plain, twill, satin, and others such as theleno weave. The most popular weave for metal and PVC coated fiberglassscreens is the plain weave. This construction offers a simple costeffective process for fabricating an insect screen. One disadvantage ofthe plain weave is that the fiber construction can be loose and unstabledepending on the openness of the fabric and rigidity of the fiber. PVCcoated fiberglass screens overcome this issue by melt flowing the PVCcoating to adhere the fibers at the intersections.

[0041] Another aspect of this invention is an insect screen of anon-metallic material that is bonded at the fiber intersections. Durablybonding polymer fibers can be particularly challenging. Adhesives can beused, however, excess adhesive may be inadvertently applied beyond thefiber intersections regions. Furthermore, adhesives tend not to be UVresistant. Another bonding approach is to use heat for melt bondingfiber at the intersections. This technique can be accomplished throughvarious processing options, one of which uses heated calendering rolls.With this approach, special care needs to be taken to avoid melting theentire fiber outside of the intersection points regions. This meltingcan cause the fiber cross-section to flow and flatten resulting in ascreen that has less light transmission and airflow. This problem isevident with PVC coated fiberglass insect screens in that the PVCcoating flows during the thermal bonding process, which decreases thedimensions of the warp and fill openings. The result is a significantloss of 10% or more in light transmission yielding a screen of onlyabout 55% light transmission. This bonding issue is typically limited tonon-metallic insect screens since the fibers of metal screens tend tooffer a more rigid and stable weave thereby negating the need forbonding of the fibers.

[0042] An inventive preferable method of bonding non-metallic fibers isthrough the use of ultrasonic energy. Heat can be generated locally atthe fiber intersections by applying ultrasonic energy through anultrasonic horn and anvil system. This process can be accomplished whenthe fabric is stationary using a plunge and activate method. Preferably,it may be accomplished in a continuous process using a horn and rotaryanvil. Use of ultrasonics for bonding fibers in insect screens hasunique inventive advantages. Since the process can generate heat forbonding isolated only to the fiber intersections, bonding can occurwithout heating the entire fiber. By controlling the applied heat, thefiber shape is less likely to distort. The result is a screen of fibersthat substantially maintain their original cross section of the fibersin the non-bonded, non-intersecting regions. The end result is an insectscreen that is substantially stable due to the bonds at fiberintersection, with very little flow of the fibers elsewhere. Thisnon-metallic screen construction can offer higher light transmission andvisual clarity properties than previously achieved.

[0043] Insect screens are available in a variety of colors ranging fromblack to green to white. Metal screens are typically painted or coatedfor color and corrosion resistance. It has been found that a darkercolor such as black is preferable in order to reduce reflective glare.Furthermore, a fiber that is opaque can reduce the transmittedrefractive glare. Clear fibers can increase the total light transmissionof a screen fabric but can suffer from reflective and refractive glarein certain applications.

[0044] Another aspect of this invention is an insect screen materialthat is suitable for mounting in a screen frame using a conventionalspline and groove attachment. The majority of insect screens used incombination with window frames utilize this method for mounting andattachment. It is preferable that the screen construction enables thismeans for mounting and attachment.

[0045] Without intending to limit the scope of the present invention,the following examples illustrate how the present invention may be madeand used.

EXAMPLE 1

[0046] An insect screen was fabricated in the following manner:

[0047] PVDF fiber was extruded using standard methodologies known in theindustry. For this example, Albany International, of Albany NY, extrudedfiber at a diameter of 0.005 inches. This fiber had an average denier of242 and average tenacity of 3.22 grams per denier. Clear fiber wasextruded.

[0048] The fiber was then woven into a plain weave construction usingstandard weaving techniques. For this example, Prodesco of Perkasie PAprovided the weaving. The fiber was woven into a 52 inches wideconstruction screen having 20 picks per inch (ppi) by 17 picks per inch(ppi). The warp and fill openings (hole sizes) were measured to be0.046″ and 0.053″ respectively.

[0049] This woven screen was then tested for light transmissionproperties. The results are listed in the table below.

EXAMPLE 2

[0050] Insect screen from Example 1 was then lightly painted with blacksemigloss spray paint. The paint used was Painter's Touch #1974 byRust-oleum Corporation. The purpose of this paint was to simulate ablack opaque fiber in order to conduct light transmission testing. Thispainted woven screen was then tested for light transmission properties.The results are listed in the table below.

[0051] The following method was used to evaluate light transmissionproperties for inventive and comparative insect screen materials. Thecomparative insect screen materials of PVC fiberglass (11 mil−18×14)(Comparative Example 1) and stainless steel (9 mil−18×14) (ComparativeExample 2) were from New York Wire Co., Mt. Wolf, PA and TWP Inc.,Berkeley, Calif. respectively.

[0052] Light Transmission Testing

[0053] The procedure to measure the optical properties of a screenmaterial makes use of a spectrometer, specifically a Perkin Elmer Lambda18 model suitable for measurements in the visible range of wavelengths.The spectrometer must have the capability to measure integratedreflectivity and transmission via an integrating sphere attachment like,for example, model RSA-PE-18 from Labsphere. The values obtained hererequire four different configurations: Specular+diffuse transmission(total transmission), Specular+diffuse reflectance (total reflectance),diffuse-only transmission and diffuse-only reflectance. The results arerecorded in each instance in absolute percentages. With reference toFIG. 2, three ports on the integrating sphere are of importance: Thefirst port is the light entry and transmission port (port 1). Thereflectance port (port 2) is used for a 100% calibration as well asreflectance measurements. Its surface normal is at an angle (8 degrees)versus the sample beam, which allows for capture of a specularlyreflected beam at the specular port (port 3). Port 1, 2 and 3 include anangle of 16 degrees. The beam size in port 1 and 2 should besignificantly larger than the openings in the screen to minimizemeasurement errors due to edge effects. The beam size used was about ⅜×⅛inches.

[0054] In Specular+Diffuse transmission mode, the sample is placed inport 1 and transmission of the beam in the forward direction (specular)as well as all hemispherically scattered transmission is recordedsimultaneously. A 100% standard must be placed in port 2. For thediffuse-only transmission, the specular component of the transmittedlight needs to be trapped by a light trap placed in port 2 with thesample in port 1.

[0055] Diffuse+Specular reflectance is measured by placing the sampleinto port 2. Care must be taken (since reflectance can be quite low)that a light trap is placed behind the sample so that any light,transmitted through the sample, cannot return back into the sphere viaport 2. Appropriate background subtraction procedures should be applied.A measurement of diffuse reflectance eliminates specularly reflectedlight by placing another light trap into port 3 while having the sample,backed by a light trap, in port 2. This will measure only that lightwhich is diffusely reflected into the intergrating sphere. Specular-onlyreflectance is calculated by subtracting diffuse-only reflectance fromtotal reflectance.

[0056] Specular transmission is meant to depict the direct light thatpasses through the screen openings excluding diffuse transmission andthe reflective components. This direct light represents the undistortedlight emitted by the image to be viewed. This value was calculated bythe following equation:

Specular transmission=total transmission−(diffuse transmission only)

[0057] Visual clarity factor is meant to describe the speculartransmission of the image to be viewed through the screen while takinginto account the negative effects of glare associated with the diffusetransmission as well as both the diffuse and specular reflective lightcomponents. This value was calculated by the following equation:

Visual clarity factor=Specular transmission−(diffuse transmissiononly+total reflectance)

[0058] The results of the testing are shown in the table below: VisualClarity Total Specular Factor Transmission Diffuse Transmission SpecTrans − Transmission Transmission Total Reflectance ReflectanceTransmission Diff Trans + (Diff Trans + Diff + Spec Only ReflectanceDiffuse only Spec only Spec Only Reflectance Reflectance)  5 mil PVDF -96.7% 14.5%  1.7% 1.6% 0.1% 82.2% 16.2% 66.0% clear (Ex. 1)  5 MilPVDF - 81.4% 1.3% 0.7% 0.6% 0.1% 80.1%  2.0% 78.1% Black (Ex. 2) 11 milPVC 56.0% 0.8% 2.5% 2.0% 0.5% 55.2%  3.3% 51.9% fiberglass - black  9mil stainless 74.3% 3.1% 9.3% 9.0% 0.3% 71.2% 12.4% 58.8% steel

[0059] As can be seen from the table above, the visual clarity of theworking examples, demonstrated by the visual clarity factor, isconsiderably better than the comparative examples. This is quite asurprising result, because the hole sizes are similar in all theexamples (working and comparative), and the pick count is higher withthe working examples. Because the inventive screens have such bettervisual clarity, they are much more desirable for the industry,fulfilling the long-felt need for screens with better visualcharacteristics.

[0060] For many screen applications such as windows, doors, screenedporches, tents, and more, a special construction of screen may berequired for substantial exclusion of insects that are smaller thantypical insects such as houseflies and mosquitoes. This insect categoryincludes smaller insects such as biting midges, known as “noseeums” orCeratopogonidae, but also includes even smaller insects commonly foundin areas near lakes, rivers, or farms. It can be desirable to excludethese insects from residential applications, recreational vehicles,screened in porches, tents, etc. while still retaining the visual andairflow benefits that insect screens are designed to offer.

[0061] Insect screens having hole dimensions of 0.040 inches willexclude some portion of these smaller insects. However, by decreasinghole dimensions further to 0.030 inches, 0.020 inches, 0.010 inches, andeven smaller, one can obtain substantial exclusion of even smallerinsects. At these smaller hole sizes in today's commercial screens, itis well known that there are significant performance compromises throughreduced visual clarity, light transmission, and air flow. Typicalcommercial examples of residential insect screens offering “noseeum”exclusion are specified having a 20×20 or 20×30 mesh.

[0062] An aspect of this invention includes the use of small diameterfibers to construct an insect screen which has small hole dimensions fortiny insect exclusion yet still offers exceptional visual clarity, lighttransmission, and air flow. It is surprising that by combining smallfibers having diameters equal to or greater than 0.002 inches and lessthan about 0.007 inches with hole dimensions of equal to or less thanabout 0.04 inches and equal to or larger than about 0.01 inches, aninventive screen can be produced which far exceeds the performance ofconventional noseeum screens.

[0063] Without intending to limit the scope of the present invention,the following examples illustrate how the present invention may be madeand used.

Comparative Examples 3 & 4

[0064] Screen material was purchased from Connecticut Screen Works inNorthford, Conn. Two screen materials were available for excludingsmaller “noseeum” type of insects. Comparative Example 3 is a PVC coatedfiberglass, 20×20 mesh with 0.013-inch fiber diameter. ComparativeExample 4 is a PVC coated fiberglass, 20×30 mesh with 0.015-inch fiberdiameter

[0065] These screen materials were measured for wire diameter and warpand fill opening dimensions. These measurements are shown in the tablebelow. This screen material was also tested for light transmissionproperties; the results also listed in the tables below.

INVENTIVE EXAMPLES 3 & 4

[0066] Inventive insect screen was fabricated in the following manner:

[0067] PVDF fiber was extruded using standard methodologies known in theindustry. For this example, fiber was extruded at a diameter of 0.003inches. This fiber had an average denier of 85 and average tenacity of4.3 grams per denier. Black fiber was extruded.

[0068] The fiber was then positioned into a mock weave constructionusing a fixturing device. This fixture enabled fibers to be placedparallel to each other at a count of 42 fibers per inch. Opposing fiberswere positioned perpendicular to the first fibers, also at 42 fibers perinch. The resulting mock weave had square holes that measured to be0.020 inches per side. This is Inventive Example 3. This basic fabricconstruction could be accomplished though various means includingstandard weaving practices. In this example, the fibers were notinterwoven, however, it should be appreciated that fibers could be fusedat their intersections if further fabric stabilization were required. Itshould be further appreciated in the event the basic fabric constructionis not made by weaving, the terms “warp” and “fill” nonetheless apply todesignate respective, relatively perpendicular directions.

[0069] Using the above procedure, Inventive Example 4 was produced usingthe same fiber diameter of 0.003 inches, however the fiber count was 21fibers per inch for both the warp and fill. The resulting holes weresquare with dimensions of 0.043 inches.

[0070] This woven screen was then tested for light transmissionproperties. The results are listed in the tables below

[0071] Example: Comparative and inventive screen materials MeasuredMeasured Warp Measured fill Wire Dia Specified Opening Opening SupplierMaterial Mesh Wire Dia (In) (In) (in) (in) Comparative PVC- 20 × 200.013 0.018 0.033 0.033 Example 3 Fiberglass Comparative PVC- 20 × 300.015 0.018 0.033 0.018 Example 4 Fiberglass Inventive PVDF 42 × 420.003 0.003 0.020 0.020 Example 3 Inventive PVDF 21 × 21 0.003 0.0030.043 0.043 Example 4

[0072] The above examples were then tested for light transmissionproperties using the methodology described previously in this patent.The results are depicted in the following table: Total TransmissionSpecular Transmission Visual Clarity Diffuse Dif Factor TransmissionTransmission Total Reflectance Reflectance Transmission Trans + SpecTrans − (Diff Diff + Spec Only Reflectance Diffuse only Spec only Speconly Reflectance Trans + Reflectance) Comparative 43.4% 0.7% 2.5% 2.4%0.1% 42.7% 3.2% 39.5% Example 3 (20 × 20) Comparative 32.3% 0.6% 2.9%2.9% 0.0% 31.7% 3.5% 28.2% Example 4 (20 × 30) Inventive 74.7% 1.3% 0.7%0.6% 0.1% 73.4% 2.0% 71.4% Example 3 (42 × 42) Inventive 87.4% 0.5% 0.4%0.4% 0.0% 86.9% 0.9% 86.0% Example 4 (21 × 21)

[0073] As can be seen from the table, the light transmission and visualclarity of the inventive examples, is considerably better than thecomparative examples. This is quite a surprising result, because thehole sizes are similar in all the examples (working and comparative),and the pick count is higher with the working examples. Because theinventive screens have such better visual clarity, they are much moredesirable for the industry, fulfilling the long-felt need for screenswith better visual characteristics.

[0074] While particular embodiments of the present invention have beendescribed herein, the present invention should not be limited to suchdescriptions. It should be apparent that changes and modifications maybe incorporated and embodied as part of the present invention within thescope of the following claims.

The invention claimed is:
 1. An insect screen comprising fibers in awarp and fill construction defining openings having a warp dimension anda fill dimension, both of said warp and fill dimensions being equal toor less than about 0.04 inches and equal to or larger than about 0.01inches, said fibers having a diameter of equal to or greater than about0.002 inches and less than about 0.007 inches.
 2. An insect screen asdefined in claim 1 wherein said diameter is equal to or less than about0.006 inches.
 3. An insect screen as defined in claim 1 wherein saiddiameter is equal to or less than about 0.005 inches.
 4. An insectscreen as defined in claim 1 wherein said diameter is equal to or lessthan about 0.004 inches.
 5. An insect screen as defined in claim 1wherein said diameter is equal to or less than about 0.003 inches.
 6. Aninsect screen as defined in claim 1 wherein said fibers are metalfibers.
 7. An insect screen as defined in claim 1 wherein said fibersare non-metallic fibers.
 8. An insect screen as defined in claim 1wherein said fibers are fluoropolymer fibers.
 9. An insect screen asdefined in claim 1 wherein said fibers are PVDF fibers.
 10. An insectscreen as defined in claim 1 wherein the screen has a visual clarityfactor equal to or greater than about 50%.
 11. An insect screen asdefined in claim 1 wherein the screen has a visual clarity factor equalto or greater than about 60%.
 12. An insect screen as defined in claim 1wherein the screen has a visual clarity factor equal to or greater thanabout 70%.
 13. An insect screen as defined in claim 1 wherein the screenhas a visual clarity factor equal to or greater than about 80%.
 14. Aninsect screen as defined in claim 1 wherein the screen has a visualclarity factor of about 85%.
 15. An insect screen as defined in claim 1further comprising a frame having a groove and spline construction, saidfibers mounted in said frame.
 16. The insect screen of claim 1 wheresaid fibers are opaque.
 17. The insect screen of claim 1 where saidfibers are clear.
 18. The insect screen of claim 1 where said fibers aredark in color.
 19. The insect screen of claim 1 wherein said total lighttransmission is equal to or greater than about 50%.
 20. The insectscreen of claim 1 wherein said total light transmission is equal to orgreater than about 60%.
 21. The insect screen of claim 1 wherein saidtotal light transmission is equal to or greater than about 70%.
 22. Theinsect screen of claim 1 wherein said total light transmission is equalto or greater than about 80%.
 23. The insect screen of claim 1 whereinsaid total light transmission is equal to or greater than about 85%. 24.The insect screen of claim 1 wherein said specular light transmission isequal to or greater than about 50%.
 25. The insect screen of claim 1wherein said specular light transmission is equal to or greater thanabout 60%.
 26. The insect screen of claim 1 wherein said specular lighttransmission is equal to or greater than about 70%.
 27. The insectscreen of claim 1 wherein said specular light transmission is equal toor greater than about 80%.
 28. A fiber insect screen comprisingnon-metallic fibers in a warp and fill construction defining openingshaving a warp dimension and a fill dimension, both of said warp and filldimensions being equal to or less than about 0.04 inches and equal to orlarger than about 0.01 inches, said non-metallic fibers intersecting atintersections wherein said non-metallic fibers are bonded at at leastsome of said intersections to form bonded intersections, and whereinsaid non-metallic fibers have a cross-section that is substantiallyround between said bonded intersections.
 29. A fiber insect screen asdefined in claim 28 wherein said bonded intersections are thermallybonded.
 30. A fiber insect screen as defined in claim 29 wherein saidbonded intersections are thermally bonded via ultrasonic energy.